Although many defective genes associated with numerous genetic diseases have been identified and characterized, because of the selective permeability of biological cell membranes, delivering required amounts of therapeutically important genes into the target body cells is often a daunting challenge.
Thus, success of gene therapy approach in treating genetic diseases depends, in a major way, on the development of efficient and safe gene delivery reagents that will facilitate the intracellular delivery of therapeutic genes into the particular body cells of a patient. Accordingly, development of safe and efficient gene delivery reagents and methods that can facilitate entry of functional genes into body cells are of great medical importance. Amphiphilic molecules containing both polar and non-polar regions in their molecular architecture have been used in delivering therapeutically important molecules into cells. This makes sense given the existence of both polar and non-polar segments in biological cell membranes. Cationic amphiphiles are the particularly important class of amphiphilic compounds used most extensively for enhancing intracellular delivery of many biologically active therapeutic compounds. Broadly speaking, at physiological pH the polar segment of cationic amphiphile interacts with the therapeutically important molecules including polyanionic macromolecular DNA, RNA, proteins etc. while the non-polar region of the cationic amphiphiles facilitate the passage of the therapeutic compounds through the non-polar part of the cell membranes.
The following references are examples of cationic amphiphiles that are known in the art to be useful for enhancing the intracellular delivery of therapeutically important molecules. In addition to the molecular structures, these prior arts contain useful information and discussion on the properties of the cationic amphiphiles those are believed to be responsible for their carrier properties.
Felgner et al., Proc.Natl.Acad.Sci. U.S.A., 84, 7413-7417 (1987), reported the first use of a highly efficient cationic lipid N-[1-(2,3-dioleyloxy)propyl]-N,N,N-trimethyl ammonium chloride(DOTMA) as the DNA transfection vector.
U.S. Pat. Nos. 4,897,355 and 4,946,787 (1990) reported the synthesis and use of N-[.omega..(.omega.-1)-dialkyloxy]-and N-[.omega..(.omega.-1)-dialkenyloxy]-alk-1-yl-N,N,N-tetrasubstituted ammonium amphiphiles and their pharmaceutical formulation as efficient transfection vectors.
Leventis, R. and Silvius, J. R Biochim. Biophys. Acta. 1023, 124-132, (1990) reported the interactions of mammalian cells with lipid dispersions containing novel metabolizable cationic amphilphiles.
U.S. Pat. No. 5,264,618 (1993) reported the synthesis and use of additional series of highly efficient cationic lipids for intracellular delivery of biologically active molecules.
Felgner et al. J.Biol.Chem. 269, 2550-2561 (1994) reported enhanced gene delivery and mechanistic studies with a novel series of cationic lipid formulations.
U.S. Pat. No. 5,283,185 (1994) reported the synthesis and use of 3β[N-(N1,N1-dimethylaminoethane)carbamoyl]cholesterol, termed as “DC-Chol”for delivery of a plasmid carrying a gene for chloramphenicol acetyl transferase into cultured mammalian cells.
U.S. Pat. No. 5,283,185 (1994) reported the use of N-[2-[[2,5-bis[(3-aminopropyl)amino]-1-Oxopentyl]aminoethyl]-N,N-dimethyl-2,3-bis-(9-octadecenyloxy)-1-Propanaminium tetra(trifluoroacetate), one of the most widely used cationic lipids in gene delivery. The pharmaceutical formulation containing this cationic lipid is sold commercially under the trade name “Lipofectamine”.
Solodin et al. Biochemistry 34,13537-13544, (1995) reported a novel series of amphilic imidazolinium compounds for in vitro and in vivo gene delivery.
Wheeler et al. Proc. Natl. Acad.Sci. U.S.A 93, 11454-11459, (1996) reported a novel cationic lipid that greatly enhances plasmid DNA delivery and expression in mouse lung.
U.S. Pat No. 5,527,928 (1996) reported the synthesis and the use of N,N,N,N-tetramethyl-N,N-bis(hydroxyethyl)-2,3-di(oleolyoxy)-1,4-butanediammonim iodide i.e pharmaceutical formulation as transfection vector.
U.S. Pat. No. 5,698,721 (1997) reported the synthesis and use of alkyl O-phosphate esters of diacylphosphate compounds such as phosphatidylcholine or posphatidylethanolamine for intracellular delivery of macromolecules.
U.S. Pat. Nos. 5,661,018; 5,686,620 and 5,688,958 (1997) disclosed a novel class of cationic phospholipids containing phosphotriester derivatives of phosphoglycerides and sphingolipids efficient in the lipofection of nucleic acids.
U.S. Pat. No. 5,614,503 (1997) reported the synthesis and use of an amphiphatic transporter for delivery of nucleic acid into cells, comprising an essentially nontoxic, biodegradable cationic compound having a cationic polyamine head group capable of binding a nucleic acid and a cholesterol lipid tail capable of associating with a cellular membrane.
U.S. Pat. No. 5,705,693 (1998) disclosed the method of preparation and use of new cationic lipids and intermediates in their synthesis that are useful for transfecting nucleic acids or peptides into prokaryotic or eukaryotic cells. These lipids comprise one or two substituted arginine, lysine or ornithine residues, or derivatives thereof, linked to a lipophilic moiety.
U.S. Pat. No. 5,719,131 (1998) has reported the synthesis of a series of novel cationic amphiphiles that facilitate transport of genes into cells. The amphiphiles contain lipophilic groups derived from steroids, from mono or dialkylamines, alkylamines or polyalkylamines.
U.S. Pat. No. 5,527,928, (1996) reported on the synthesis and transfection biology of a novel cationic lipid namely, N,N,N′,N′-tetramethyl-N,N′-bis (2-hydroxyethyl)-2,3-di(oleoyloxy)-1,4-butaneammonium iodide.